Quick answer. Pure henna (Lawsonia inermis, mehndi) is a natural colourant: its pigment, lawsone, binds to the hair shaft, giving reddish-auburn colour, grey coverage and a glossier, thicker look. That's a cosmetic effect, not hair growth, and it doesn't undo greying. It can feel drying if overused, so condition after. The real hazard is "black henna" cut with PPD, which can cause severe allergic reactions; and henna can trigger haemolysis in people with G6PD deficiency, so be cautious, especially with infants, children and in pregnancy.
Almost every Indian household has a henna story, but is it good for your hair or drying it out, will it cover greys, and what's the "black henna" danger about?
What henna actually is — and what "black henna" is not
Henna is the powdered leaf of Lawsonia inermis, or mehndi. Its colour comes from lawsone, a pigment that binds to keratin and stains a reddish-orange to auburn tint onto each strand. It coats the shaft rather than reaching the cortex like chemical dye, so on its own it can't give jet-black hair.
"Black henna" is a different, riskier product, cut with para-phenylenediamine (PPD) to force a near-black stain. In one analysis PPD appeared in every black-henna sample (roughly 0.38–29.5%), while natural red henna had none or only traces [2]. The danger is the additive, not the leaf.
What henna can really do (and what it can't)
Pure henna is about colour, not biology: the glossier, thicker look is a cosmetic surface effect, not growth or repair. Claims that it "boosts circulation" or "repairs damage from within" are marketing, not evidence; its cooling scalp use is traditional, not clinical.
Henna myths, honestly checked
Myth: henna grows hair
No. It only coats the shaft; nothing reaches the follicle, so hair looks thicker but doesn't grow.
Myth: henna can undo greying
It covers grey by staining it; it doesn't change greying or stop new grey at the roots. (See amla and premature greying.)
Myth: henna always damages hair
Pure henna doesn't strip or bleach hair; dryness comes from overuse or skipping conditioner, and real harm comes from PPD "black henna," not the leaf [1].
How to apply henna safely, step by step
- Patch-test first. 48 hours before, dab paste behind your ear; itching, redness or blistering means stop, especially near-black products.
- Mix and rest. Stir pure henna powder with warm water (lemon, tea or curd optional); rest a few hours so colour releases.
- Apply with gloves to clean, dry hair, roots to ends.
- Leave 2–4 hours, not overnight. Longer only deepens colour and dries hair.
- Rinse, then condition. Skip shampoo for a day so colour sets; a warm-oil massage offsets dryness.
- Reapply every 4–6 weeks, not weekly; over-frequent henna leaves hair stiff and dry.
The safety warnings that matter: "black henna" and G6PD
"Black henna" and PPD. The hazard is the PPD added to darken it. PPD can cause severe allergic contact dermatitis (blistering, swelling, often within a day or two [5]) and can sensitise you for life, so people react to ordinary hair dye years after a single "black henna" tattoo [1]. Since natural red henna shouldn't contain PPD [2], avoid anything sold as "black henna" or fast-staining black kits. If a rash, blistering, swelling or breathing trouble follows, seek medical care.
G6PD deficiency. Lawsone can trigger haemolysis (the breakdown of red blood cells) in people with G6PD deficiency, an inherited condition common in India. The serious cases are in newborns and young children: a review of 31 paediatric cases recorded life-threatening anaemia and severe jaundice, some needing blood transfusion [3], and henna on G6PD-deficient newborns has triggered haemolytic crises [4]. The risk is low for most healthy adults but real for infants, young children and pregnancy. If unsure of your G6PD status, get medical advice before using henna on a baby or child, and watch for unusual tiredness, pallor or dark urine.
When NOT to use henna — cautions
- "Black henna" or a known PPD allergy: avoid entirely; a past reaction can flare worse.
- G6PD deficiency, infants and young children: avoid henna on babies and check G6PD status first.
- Pregnancy and lactation: be cautious and take medical advice, especially if G6PD status is unknown.
- Broken, irritated or eczema-prone scalp: patch-test, and skip if it stings.
- Real hair fall: sudden shedding, widening partings or bald patches need a doctor or trichologist. Henna is a colourant, not a hair-fall remedy.
If you're pregnant, lactating, on medication or unsure of your G6PD status, consult your doctor before using henna.
Our take: where henna fits an honest hair routine
Used honestly, henna is an occasional natural colour ritual, not a hair-fall or growth fix.
Its one downside, dryness on the lengths, is easy to manage with oil. A Bhringraj-amla conditioning oil such as KayaSuddhi's Bhringraj Hair Oil supports a weekly warm-oil massage and everyday scalp care, the step that pairs with an occasional henna colour. For the herbs Ayurveda leaned on, see our hair-oil comparison and weekly routine.
Frequently asked questions
Does henna cover grey hair — and does it reverse greying?
Henna covers grey by staining those strands reddish-auburn, reliably. But it does not reverse or stop greying; new grey keeps appearing at the roots, so colour needs topping up every 4–6 weeks.
Does henna damage or dry out hair?
Pure henna doesn't strip or bleach hair; the dryness people notice comes from overuse or skipping conditioner, so condition after. The real damage risk is PPD "black henna" [1].
What is "black henna" and is it safe?
No. "Black henna" contains para-phenylenediamine (PPD), which can cause severe allergic contact dermatitis and sensitise you for life [1][5]. Natural red henna shouldn't contain PPD [2]. Avoid it.
Is henna safe during pregnancy or for babies?
Be cautious. Henna can trigger haemolysis in people with G6PD deficiency, with serious cases in newborns and young children [3][4]. Avoid it on babies; if pregnant or unsure of your G6PD status, ask your doctor.
Related reading
- Ayurvedic hair care: the complete India guide — the full guide, plus our deep-dives on hair oils, amla and greying and a weekly routine.
Sources
- Redlick F, DeKoven J. Allergic contact dermatitis to paraphenylendiamine in hair dye after sensitization from black henna tattoos: a report of 6 cases. CMAJ. 2007;176(4):445-446. PMID 17296954. DOI 10.1503/cmaj.061109.
- Al-Suwaidi A, Ahmed H. Determination of para-Phenylenediamine (PPD) in Henna in the United Arab Emirates. International Journal of Environmental Research and Public Health. 2010;7(4):1681-1693. PMID 20617053. DOI 10.3390/ijerph7041681.
- Al-Hinai A, AlSawafi AS. Severe Hyperbilirubinemia Secondary to Henna Application in a Neonate With G6PD Deficiency: A Case Report and Literature Review. Cureus. 2023;15(2):e34540. PMID 36879691. DOI 10.7759/cureus.34540.
- Kandil HH, al-Ghanem MM, Sarwat MA, al-Thallab FS. Henna (Lawsonia inermis Linn.) inducing haemolysis among G6PD-deficient newborns. A new clinical observation. Annals of Tropical Paediatrics. 1996;16(4):287-291. PMID 8985525.
- DermNet NZ. Allergy to paraphenylenediamine (PPD). Accessed 27 June 2026.
Educational use only — not medical advice. These statements have not been evaluated by AYUSH or FSSAI as treatment claims. KayaSuddhi products are purely herbal and not intended to diagnose, treat, cure, or prevent any disease. Results may vary. Please consult your physician or a qualified BAMS-certified Ayurvedic practitioner before starting any new supplement — especially if you are pregnant, breastfeeding, on prescription medication, or managing a chronic condition.
Written & researched by
The KayaSuddhi Team
We are a small team of Ayurveda writers, researchers and reviewers in Delhi NCR. We track the health questions real people are asking, read the latest studies, and turn them into honest, practical guides — so you can make informed choices, not follow hype.
